Increased intracranial pressure and hepatic encephalopathy in chronic liver disease

Increased intracranial pressure is present in more than 80% of patients with fulminant hepatic failure. However, patients with encephalopathy secondary to chronic liver disease are thought not to develop elevated intracranial pressure. We report two patients with chronic liver disease in hepatic coma with raised intracranial pressure documented by an epidural intracranial pressure monitor. One patient rapidly deteriorated to coma over a period of 4 h. The other patient progressively worsened following intravenous sedation administered during upper endoscopy. Both patients had generalized tonic-clonic seizures, and one demonstrated decerebrate posturing and papilledema. Although all metabolic and structural abnormalities should be excluded in patients with hepatic encephalopathy, if the etiology remains in question, the possibility of increased intracranial pressure should be considered in patients with chronic liver disease.

Slow injection does not prevent midazolam-induced ventilatory depression

To determine whether the risk of midazolam-induced ventilatory depression is related to the rate of midazolam administration, we compared the effect of rapid (over 15 s) and slow (over 5 min) administration of midazolam (0.1 mg/kg IV) on the hypercarbic ventilatory response of 10 healthy volunteers. During the first 5 min after the start of midazolam injection, the slope of the ventilatory response to CO2 was significantly lower when the subjects received midazolam rapidly (P less than 0.001). However, after completion of the infusion (between 5 and 20 min), depression of the CO2 response curve slope was independent of the rate of midazolam administration. Similarly, although minute ventilation and tidal volume measured at an end-tidal CO2 tension of approximately 46 mm Hg decreased more quickly after rapid administration of midazolam (P less than 0.001), these variables did not differ significantly between the two rates of administration once the slow infusion was complete. These results suggest that slow administration of midazolam provides no independent protection from respiratory depression.

Time course of ventilatory depression following induction doses of propofol and thiopental

To improve our understanding of the respiratory pharmacology of intravenous induction agents, the authors compared the acute effects of intravenous (iv) propofol 2.5 mg.kg-1 and iv thiopental 4.0 mg.kg-1 on the ventilatory response to CO2 (VeRCO2) of eight healthy volunteers. The slope of VeRCO2 decreased from 1.75 +/- 0.23 to a minimum of 0.77 +/- 0.14 1.min-1.mmHg-1 (mean +/- standard error) 90 s after propofol; similarly, the slope of VeRCO2 decreased from 1.79 +/- 0.22 to a minimum of 0.78 +/- 0.23 l.min-1.mmHg-1 30 s after thiopental. For both drugs, the slope was less than control in the 0.5-5-min period after injection (P less than 0.05). The slope returned to baseline within 6 min after thiopental; in contrast, after propofol, the slope remained less than control for the entire 20-min follow-up period (P less than 0.05 at 6-10, 11-15, and 16-20 min after injection). Also, from 6-10, 11-15, and 16-20 min after injection, the slope was less after propofol than at corresponding times after thiopental (P less than 0.05). Recovery of consciousness was approximately 4 min slower after propofol than after thiopental; nonetheless, awareness scores returned to baseline within 14 min after both drugs. The authors conclude that propofol 2.5 mg.kg-1 iv produces longer-lasting depression of VeRCO2 than a 4.0 mg.kg-1 iv dose of thiopental; after propofol, ventilatory depression may persist despite apparently complete recovery of consciousness.

Ibuprofen provides longer lasting analgesia than fentanyl after laparoscopic surgery

The authors compared the analgesic efficacy of one dose of oral ibuprofen with that of intravenously administered fentanyl for relief of pain after outpatient laparoscopic surgery. Thirty healthy female patients received either 800 mg of oral ibuprofen preoperatively or 75 micrograms of intravenous fentanyl intraoperatively plus respective intravenous or oral placebos in a randomized, double-blind manner. Patients recorded their degree of pain and nausea in the recovery room, in the same-day surgery stepdown unit, during the ride home, and upon arrival at home. The postanesthesia care nurse recorded the amount of fentanyl and droperidol needed to treat pain and nausea in the recovery room. Patients who received ibuprofen were more comfortable in the stepdown unit (P less than 0.05) and after arrival home (P less than 0.05) than those in the fentanyl group. Additionally, patients who received ibuprofen had lower nausea scores in the step-down unit (P less than 0.05); this may have been related to the lower total fentanyl dose in these patients. The authors conclude that ibuprofen may be a useful alternative to fentanyl for providing postoperative analgesia for outpatient surgery.

Flumazenil antagonism of midazolam-induced ventilatory depression

Flumazenil, a benzodiazepine antagonist, reliably reverses midazolam-induced sedation; however, its effect on respiratory depression has not been established completely. Twelve healthy volunteers received sufficient midazolam (0.13 +/- 0.01 mg.kg-1 mean +/- SE) to render them unresponsive to verbal command; they then received flumazenil 1.0 mg or placebo (flumazenil vehicle) in a randomized, double-blind fashion. Ventilatory drive was measured before and after administration of midazolam, as well as 3, 30, 60, and 120 min after administration of flumazenil or placebo. Seven to 30 days later, the study was repeated, with subjects receiving placebo or flumazenil (whichever they had not received during their first trial). Midazolam caused significant decreases in the slope of the CO2 response (-29 +/- 5%; P less than 0.005); minute ventilation (VE) at end-tidal CO2 tension (PETCO2) = 46 mmHg (-28 +/- 4%; P less than 0.001), and tidal volume at PETCO2 = 46 mmHg (-44 +/- 4%; P less than 0.005). Three minutes after intravenous administration of flumazenil 1.0 mg, VE46 and tidal volume increased to 108 +/- 6% and 105 +/- 6%, respectively, of their premidazolam values; at the same time after administration of placebo, VE46 and tidal volume remained significantly depressed (between groups, P less than 0.005 for each variable). Thirty minutes later, these variables did not differ between groups, probably because the effects of flumazenil and midazolam were diminishing.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of epidural and patient-controlled intravenous morphine following joint replacement surgery

The authors conducted a randomized, prospective study comparing epidural morphine with patient-controlled intravenous (iv) morphine in 30 patients recovering from total hip or total knee arthroplasty. Six, 18, and 24 hr postoperatively, patients used a 10 cm visual-analogue scale to indicate both their current degree of discomfort and the maximum discomfort they had experienced since the previous evaluation. Pain at the time of evaluation did not differ between patients receiving epidural (2.6 +/- 0.4 cm, mean +/- SEM) and patient-controlled iv morphine (3.4 +/- 0.3 cm). However, patients who received epidural morphine recalled less pain during the period preceding evaluation (4.2 +/- 0.5 cm) than did those receiving patient-controlled analgesia (5.5 +/- 0.4 cm, P less than 0.05). Patients receiving epidural morphine were more likely to require treatment for pruritus (4 of 15) than patients who received patient-controlled iv morphine (none of 15, P less than 0.05). Minimum respiratory rates were lower in patients receiving epidural morphine (15.0 +/- 0.3) than in those receiving patient-controlled analgesia (16.5 +/- 0.4, P less than 0.05), but no patients required treatment for respiratory depression. The authors conclude that epidural morphine may provide more consistent analgesia following joint replacement surgery than patient-controlled morphine; however, there is a higher incidence of side-effects with the epidural technique.

The air test as a clinically useful indicator of intravenously placed epidural catheters

The authors performed a clinical trial in 313 patients in labor to determine the safety and efficacy of an air test for unintentional intravenous placement of epidural catheters. Following routine aspiration for blood and cerebrospinal fluid, 1 ml of air was injected through each epidural catheter while heart tones were continually monitored with a Doppler ultrasound probe placed over the maternal precordium. In 281 patients, Doppler heart tones did not change following air injection (negative air test). All but eight of these patients developed an adequate level of analgesia following anesthetic administration, and no patients with negative air tests developed signs or symptoms of local anesthetic toxicity (false-negative rate, 0%; 95% confidence limits, 0.0-1.1%). Doppler heart tone changes followed air injection in 22 cases (positive air test). In 16 of these, intravenous catheter position was subsequently shown by aspiration of blood from the catheter or by the use of test doses consisting of local anesthetics with or without epinephrine. In six cases, adequate levels of analgesia developed despite a positive air test (false-positive rate, 2%; 95% confidence limit, 0.7-4.3%). None of the 303 patients receiving the air test developed any complications attributable to the injection of air (95% confidence limits, 0.0-1.0%). The authors conclude that air, with precordial Doppler detection, is a safe and effective test for identifying intravenously located epidural catheters.

Hepatic cyst infection in autosomal dominant polycystic kidney disease

To characterize the syndrome of hepatic cyst infection in autosomal dominant polycystic kidney disease (ADPKD) and to review its diagnosis and management, we retrospectively studied five such cases in patients from our institution and nine detailed case reports from the literature. The clinical manifestations were an acute (58%) or subacute (42%) febrile illness, typically associated with tenderness in the right upper quadrant, leukocytosis, a very high erythrocyte sedimentation rate, but minor abnormalities of liver function tests. Bacteremia was present in 7 of 11 patients. Enterobacteriaceae grew in pure culture from the cyst fluid in 9 of 12 patients. Complex cysts were observed by ultrasonography (in four of eight patients), computed tomography (in six of nine), and magnetic resonance imaging (in two of two). 111In leukocyte scans were positive in all four patients in whom they were done, and 67Ga scans were positive in only one of three patients. An unfavorable outcome was observed in six of seven patients treated with only antibiotics, in contrast with one of seven patients who received antibiotics and early drainage. In two patients, ciprofloxacin cyst levels were 2.3 and 4.8 times higher than the level in serum; in a third patient, cyst levels remained in therapeutic range 30 hours after the last dose of ciprofloxacin, at which time serum levels were undetectable. Clinical and laboratory features and the use of modern scanning techniques facilitate a prompt diagnosis of infection in hepatic cysts in ADPKD. The treatment of choice is a combination of percutaneous drainage and antimicrobial therapy.

Persistent centrilobular necroses in hepatic allografts

A biopsy study of 60 allografts from 53 patients after orthotopic liver transplantation (OLT) revealed prominent centrilobular necrosis (CN) in 18% of the grafts that were suitable for analysis. The lesions often had a "punched-out" appearance, sometimes with unusual features such as giant cell formation. Persistent CN developed 4 weeks to 6 months after OLT, and persisted in two cases for 2 years and longer. In some instances, CN disappeared or healed by scarring. We found no association between CN and rejection arteritis or arteriopathy. Ductopenic (chronic) rejection subsequently occurred in six of eight livers with CN. Overall, patients with persistent CN had a worse prognosis than control patients. A comparison of cases with matched controls failed to reveal significant differences with respect to perioperative factors such as ischemia time, immunologic test results such as lymphocyte crossmatches, drug administration--in particular, of azathioprine, frequency of cellular (acute) rejection or infection episodes, or frequency of complications affecting major hepatic vessels or bile ducts. Morphologic evidence suggests that in some instances, rejection-induced endotheliitis/phlebitis of hepatic vein branches may lead to sinusoidal outflow blockage, sinusoidal dilatation, and dropout of hepatic cell plates. Although potentially reversible conditions such as ischemia or adverse drug reactions are among the possible causes of CN, severe rejection leading to ductopenia appears to be the most important underlying condition. Thus, presence of CN in repeated biopsy specimens from allografts should be considered a warning sign of irreversible rejection.

Nasal oxygen alleviates hypoxemia in colonoscopy patients sedated with midazolam and meperidine

A randomized study was carried out to determine whether the administration of oxygen (3 liter/min) via nasal prongs significantly affects arterial oxygenation during colonoscopy in patients sedated with intravenous midazolam (2.6 +/- 0.2 mg, means +/- SE) and meperidine (48 +/- 3 mg). Patients who received supplemental oxygen were less likely to become hypoxic (pulse oximeter reading, SpO2 less than 90%) than those who breathed room air (10 of 28 vs. 22 of 28, p less than 0.005). Similarly, the total time during which SpO2 was below 90% was significantly less in patients receiving nasal oxygen (0.7 +/- 0.3 min) than in patients breathing room air (9.7 +/- 1.9 min, p less than 0.001). Minimum oxygen saturations were significantly higher in patients receiving oxygen (90.6 +/- 0.8%) than in patients breathing air (86.5 +/- 0.8%, p less than 0.001). In patients breathing air, there was a significant negative correlation between the dose of meperidine and the minimum observed oxygen saturation; conversely, midazolam dose did not correlate with indices of hypoxemia. The authors conclude that administration of oxygen via nasal prongs can reduce the risk of hypoxemia during colonoscopy. However, since hypoxemia may occur even when nasal oxygen is given, continuous monitoring of arterial oxygenation is recommended.

Air: an effective indicator of intravenously located epidural catheters

The authors conducted a two-part study to evaluate the efficacy of 1 ml of air as a "test dose" for detection of intravenously located epidural catheters. In part 1, a Doppler fetal heart rate monitoring probe was placed over the precordium of 33 laboring patients in whom functioning epidural catheters were in place. Each patient received, more than 90 s apart, in random order: 10 ml of agitated saline (containing less than 0.5 ml of air microbubbles) via a peripheral vein; 2 ml of air via the epidural catheter; and a sham injection (i.e., nothing injected). In all 33 cases, a blinded observer identified Doppler changes 10-30 s following the injection of air (microbubbles) via peripheral vein. Doppler changes were never heard following epidural air injection (P less than 0.001 compared with iv air microbubble injection) or the sham injection (P less than 0.001 compared with iv air microbubble injection). In part 2, the authors listened for Doppler heart tone changes while injecting 1 ml of air via catheters that were accidentally inserted in the epidural veins of five other patients. Unequivocal Doppler changes compatible with intracardiac air always occurred within 3 s, and no signs or symptoms of air embolism developed. The results suggest that 1 ml of air may be a suitable indicator of iv epidural catheter location.

Spread of analgesia and ventilatory response to carbon dioxide following epidural somatostatin

The effects of somatostatin, injected into the epidural space, on analgesia and control of ventilation were studied in 25 patients aged 41 +/- 9 yrs (mean +/- SD). The patients were allocated to three groups to receive: Group I--1 mg of somatostatin in 2 ml saline (n = 13); Group II--1 mg of somatostatin in 10 ml saline (n = 6); and Group III--somatostatin in a loading dose of 250 micrograms followed by an infusion of 125 micrograms h-1 (n = 6). Segmental cutaneous analgesia, assessed by pinprick, without loss of thermal sensibility or motor blockade was found in all patients. Onset times and durations of analgesia were 15 +/- 2 min and 69 +/- 19 min (mean +/- SD) in Group I and 14 +/- 2 min and 68 +/- 11 min in Group II. The extent of dermatome analgesia at 30 min and 60 min after somatostatin injection, respectively, was: T6 +/- 2 to T12 +/- 1, T4 +/- 2 to L1 +/- 2 in Group I, and T7 +/- 3 to L1 +/- 3, T3 +/- 1 to T12 +/- 2 in Group II. Continuous analgesia with onset of 16 +/- 2 min and extending from T7 +/- 1 to T12 +/- 1 was observed in Group III. No side-effects were observed. The control of ventilation studies in eight patients in Group I by the Read's rebreathing method did not show any significant change.

New discharge criteria decrease recovery room time after subarachnoid block

The authors completed a two-phase study to determine criteria that might predict hemodynamic stability during recovery from subarachnoid block (SAB). Patients' supine and sitting (2 min) blood pressures were determined at 30-min intervals in the recovery room (RR). In the first group of 26 patients, retrospective analysis revealed that the orthostatic decrease in mean arterial pressure (MAP) never exceeded 15% following two successive orthostatic decreases of 10% or less. This finding was validated prospectively in a second group of 26 patients. Following two successive orthostatic MAP decreases of 10% or less, none of 65 orthostatic challenges resulted in an MAP decrease of more than 15%; conversely, in the absence of two successive MAP decreases of less than 10%, 5 of 51 orthostatic challenges resulted in an MAP decrease of greater than 15% (P less than 0.02). Had patients been discharged from the RR based on two successive MAP decreases of less than 10%, 35 of 52 patients could have been discharged from the RR 76 +/- 6 min (mean +/- SE) sooner than they would have under usual empirical discharge criteria of supine hemodynamic stability, regression of sensory level to T10, and return of toe movement. Following SAB, hemodynamic stability may return before sensory and motor function; for many patients, orthostatic testing following SAB may safely decrease the amount of time spent in the RR.

Acute hepatic failure: the emerging role of orthotopic liver transplantation

From 1985 through 1987, we diagnosed acute hepatic failure in 13 patients. Spontaneous recovery occurred in three of these patients. Eight patients underwent liver transplantation, five of whom survived and three of whom died. In addition, two patients died before undergoing transplantation. The survival rate of 62% was better than that among our previous series of similar patients. This improvement seems to be related to the use of orthotopic liver transplantation as a therapeutic alternative among these patients. One of the three patients who died after liver transplantation had normal liver function, but respiratory failure caused by Pneumocystis carinii developed 4 months after the transplantation. The surgical procedure was less difficult in patients with acute fulminant hepatitis than in those with chronic liver disease because fewer problems arose from adhesions, venous collaterals, and ascites. The emerging role of orthotopic liver transplantation in patients with acute hepatic failure is demonstrated by the improvement of survival rates observed by various groups, including ours, when this therapeutic modality is available.

Ventilatory response to CO2 following intravenous ketamine in children

The effects of intravenous ketamine (bolus of 2 mg.kg-1 followed by a continuous infusion at a rate of 40 micrograms.kg-1.min-1) on ventilatory response to carbon dioxide were studied in nine children ranging in age from 6 to 10 yr and in weight from 20 to 48 kg. Ketamine did not affect resting respiratory rate, tidal volume, end-tidal CO2 tension (PETCO2), or minute ventilation. Five minutes after the ketamine bolus, the slope VE/PETCO2 decreased significantly (P less than 0.05) from 1.71 +/- 0.47 to 1.05 +/- 0.23 1.min-1.mmHg-1 (mean +/- SD). After 30 min of continuous iv ketamine infusion, the slope returned to 1.65 +/- 0.44 1.min-1.mmHg-1, a significantly higher value (P less than 0.05) compared with the nadir and not significantly different from control. The minute ventilation at a PETCO2 of 60 mmHg decreased from 824 +/- 98 to 626 +/- 26 ml.kg-1.min-1 5 min after iv ketamine, and remained depressed (640 +/- 125 ml.kg-1.min-1 P less than 0.05) throughout the 30-min ketamine infusion. In addition, the slope VT/PETCO2 and the VT 60 did not change during the study; nonetheless, the slope f/PETCO2 and the f 60 decreased significantly following iv bolus ketamine, and the f 60 remained significantly decreased following ketamine infusion. The authors conclude that clinically useful doses of iv ketamine significantly alter ventilatory control in children.

Biliary copper excretion by hepatocyte lysosomes in the rat. Major excretory pathway in experimental copper overload

We investigated the hypothesis that lysosomes are the main source of biliary copper in conditions of hepatic copper overload. We used a rat model of oral copper loading and studied the relationship between the biliary output of copper and lysosomal hydrolases. Male Sprague-Dawley rats were given tap water with or without 0.125% copper acetate for up to 36 wk. Copper loading produced a 23-fold increase in the hepatic copper concentration and a 30-65% increase in hepatic lysosomal enzyme activity. Acid phosphatase histochemistry showed that copper-loaded livers contained an increased number of hepatocyte lysosomes; increased copper concentration of these organelles was confirmed directly by both x ray microanalysis and tissue fractionation. The copper-loaded rats showed a 16-fold increase in biliary copper output and a 50-300% increase in biliary lysosomal enzyme output. In the basal state, excretory profiles over time were similar for biliary outputs of lysosomal enzymes and copper in the copper-loaded animals but not in controls. After pharmacologic stimulation of lysosomal exocytosis, biliary outputs of copper and lysosomal hydrolases in the copper-loaded animals remained coupled: injection of colchicine or vinblastine produced an acute rise in the biliary output of both lysosomal enzymes and copper to 150-250% of baseline rates. After these same drugs, control animals showed only the expected increase in lysosomal enzyme output without a corresponding increase in copper output. We conclude that the hepatocyte responds to an increased copper load by sequestering excess copper in an increased number of lysosomes that then empty their contents directly into bile. The results provide direct evidence that exocytosis of lysosomal contents into biliary canaliculi is the major mechanism for biliary copper excretion in hepatic copper overload.

Analgesia and ventilatory response to carbon dioxide after intramuscular and epidural alfentanil

The analgesic and ventilatory depressant effects of epidural and intramuscular alfentanil (15 micrograms/kg) were compared in two groups of seven healthy unpremedicated subjects. Fifteen minutes after IM injection, the slope of the ventilatory response to CO2 decreased significantly (from 2.72 +/- 0.34 to 1.8 +/- 0.20 L.min-1.mmHg-1) while assessment of periosteal analgesia showed no change. After epidural injection, the slope of the ventilatory response to CO2 decreased significantly (from 2.32 +/- 0.42 to 1.61 +/- 0.29, 1.51 +/- 0.29, and 1.53 +/- 0.21 L.min-1.mm Hg-1) at 15, 45, and 90 minutes (x +/- SD, P less than 0.05), and there was significant periosteal analgesia of the tibia (15 and 30 minutes after injection) and of the radius (30 to 90 minutes after injection). Throughout the study, plasma alfentanil levels were similar after intramuscular and epidural injection. These results suggest that epidural alfentanil induces ventilatory depression due to the rostral spread of the drug rather than to systemic absorption.

Sedative doses of midazolam depress hypoxic ventilatory responses in humans

The effect of midazolam on the hypoxic ventilatory response of eight healthy volunteers was examined during isocapnic rebreathing. The magnitude of the slope of the ventilatory response to hypoxia (VE vs SaO2) decreased from 1.48 +/- 0.24 to 0.70 +/- 0.13 L.min-1.%SaO2(-1) (means +/- SE, P less than 0.005) after midazolam 0.1 mg/kg IV. The calculated ventilation at an arterial saturation of 90% also decreased from 28.6 +/- 4.4 to 19.9 +/- 2.7 L/min (P less than 0.05). Before midazolam, hypoxia to an SaO2 of 75 +/- 2% was associated with a 23 +/- 3 beats/min increase in heart rate; after midazolam, the increase in heart rate with hypoxia was only 4 +/- 2 beats/min (P less than 0.001). Additionally, a double-blind crossover study evaluated the effect of physostigmine on awareness and hypoxic ventilatory response after midazolam. The change in hypoxic response slope after physostigmine 2.0 mg IV (an increase of 0.28 +/- 0.34 L.min-1.%SaO2(-1] did not differ significantly from that after placebo (an increase of 0.03 +/- 0.22 L.min-1.%SaO2(-1], although physostigmine significantly increased awareness. It is concluded that a sedative dose of midazolam depresses hypoxic ventilatory response and attenuates the hyperpnea and tachycardia associated with hypoxemia. Furthermore, physostigmine-glycopyrrolate reversal of midazolam-induced sedation was associated with nausea (five subjects), vomiting (three subjects), and tachycardia without reversal of the depressed hypoxic ventilatory response.